This invention relates to the dyeing of a continuous web of fabric materials and the like, and more particularly to the patterned dyeing or printing of such material by the rapid controlled deflection of the paths of a plurality of dye streams onto or away from the moving web.
Various methods have been used for the patterned dyeing of continuous webs of textile fabrics such as pile carpets to produce various patterns on the web. Penetration of the dyestuffs into the pile and pattern definition or resolution have been major considerations in the prior patterned dyeing of such fabrics. In comparison to the printing of flat textiles or other non-pile material on which dye penetration is not a factor, pile fabric must be deeply penetrated to obtain quality results. Good definition can be obtained by contact printing on flat goods but not on pile fabrics. For example, heat transfer printers which use a paper substrate carrying a patterned heat sensitive dye placed in direct contact with the web to transfer the dye by the application of heat to the paper may be used to produce good resolution on flat goods. The pile height of pile fabrics, however, preclude such a process since the dye cannot penetrate deeply into the pile.
Other prior art printing forms, such as the use of dye containing rollers engraved with a pattern sequentially contacting the fabric, and various screen contacting processes have also suffered from deficiencies relating to dye penetration. Various proposals using rollers and screen printers together with systems applying a vacuum on the opposite side of the fabric from the dye have met with limited success. Screen printers, for example, provide excellent pattern definition but are relatively slow, e.g. in the order of 20 feet per minute. Moreover, when a pattern change is required each set of pattern screens must be replaced by another set thereby resulting in long periods in which the machine is inoperative. Thus, the overall efficiency of such printers is relatively low, especially where short runs of one pattern are made. Pattern rollers also suffer from such disadvantages.
More recently various processes for the printing of textiles have utilized controlled jets of dye sprayed onto the moving fabric web. In such systems a plurality of dye nozzles or spray jets extend from a dye manifold or applicator transversely across the moving web and a number of such applicators, each controlling a different color dye, may be spaced in the direction of movement of the web. Each individual nozzle or jet is controllably activated by suitable electronic, pneumatic or mechanical means to dispense the dye onto the moving web under the control of a pattern controller. Control of the actuation of the individual dye streams determines not only the pattern definition, but also the speed of printing. Individual solenoid valves have been used for selectively and individually controlling the supply of dye to the nozzles, as have been pinching bars to control the flow of dye through flexible dye delivery tubes. Other prior art approaches have used electromagnetically operated needle valves to individually control the application of the dye.
Other proposals, such as illustrated in U.S. Pat. Nos. 3,443,878 and 3,570,275, employ a plurality of continuously flowing dye streams which are selectively deflected by pneumatic jets, electrostatic or electromagnetic deflection devices, or stream blocking and unblocking elements either to permit impingement of the dye stream onto a moving inclined web of fabric or recirculation to a dye supply reservoir. The only known practical utilization of such proposals is the Millitron process which utilizes a controlled pneumatic stream to deflect the dye streams selectively to divert the dye streams out of the path of the fabric and into a catch basin from which the dye is recirculated. This system uses a plurality of solenoid valves controlled by a pattern control system for each dye jet to effect impingement of compressed air against the dye streams to deflect the dye. This system and the controls therefor are disclosed in at least U.S. Pat. Nos. 3,894,413; 4,116,626 and 4,170,883.
In another system, which is disclosed in U.S. Pat. No. 4,341,098 assigned to the common assignee as the present invention, pinch tube valves are provided for pinching flexible tubes to selectively control the flow of dye onto the moving web. That system was devised to overcome the disadvantages of commercially available solenoid liquid control valves, which not only are too slow to permit precise control of small amounts of dye for good pattern definition, but additionally are not drip free. In prior art systems which used solenoid valves to control the flow of liquid, relatively high viscosity dyes and small nozzles had to be employed to prevent dripping. A drawback to the use of high viscosity dye is that additional dye pressure is required to penetrate high pile fabrics, such as carpet, effectively.
A disadvantage of the known systems which use solenoid valves to control pneumatic deflectors, or pinch tube valves to control the flow of dye, is the relatively slow response speeds inherent in such valves. Thus, the speed at which printing can be performed is limited if quality pattern definition is to be obtained.